Photosynth needs a FOV to display the image correctly - a value of "0" is not accepted. If you don't know the exact (horizontal) FOV of your image, an approximate value should be sufficent (e.g. a 50mm lens has a FOV of ~38 degrees)

projecting as rectiliniar and using the real fov, as generated by ptgui, renders an usable image, with the corners of the image displayed at a steep angle. using the cilindrical projection gives curves the image. in your image of the altar I see a good perspective, the only thing I think of is using a very narrow angle for the rectiliniar projection for a simple, square image display.